Electric furnace



Oct. 16, 1928.

R. B. LINCOLN ELECTRIC FURNACE Filed Feb. 16, 1.927

Fig.1.

Fig 2 6 as so M WVENTOR 3% E 6 immmai n,

B [5) f #:WORNEY Patented Oct. 16 1928-.

UNITED STATES PATENT OFFICE.

ROLLO B. LINCOLN, OF WILKINSBURG, PENNSYLVANIA, ASSIGNOR TO WESTING- HOUSE ELECTRIC & MANUFACTURING COMPANY, A CORPORATION OF PENNSYL- VANIA.

ELECTRIC FURNACE.

Application filed February 16, 1927. Serial No. 168,577.

therefrom while the furnace is hot.

Another object of. my invention is the pro vision of an opening in a wall of said furnace, through which the resistance units may be withdrawn, the effective length of which is substantially less than the total width of the units to be removed therethrough, so that the structural strength of the furnace wall is not seriously impaired.

In the present embodiment of my invention, I provide a plurality of resistance units disposed along the walls of a furnace chamber, restricted openings or slots being pro vided in the roof of the furnace to permit the removal of a plurality of the resistance units through each opening. Preferably, I provide an opening or slot for each three adjacent units the effective length of which is substantially less than the combined widths of the units disposed thereunder.

Terminal extensions are provided on each unit which project through the slots to provide a means for electrically connecting said units to a son: cc of power, and which terminal extensions partiall close said slots,-under normal conditions. omplete closure of the slots is effected by a block of refractory material inserted in each slot in cooperating 6. Access may be had to the furnace chamrelation to the terminal extension of the central unit thereof.

Inthe drawings, Figure 1 is-a plan view .of a furnace embodying my invention Fig. 2 is a view, in. section, on the line IIII of Fig. 1; and j Fig. 3 is a fview, in section, on the line III-III of Fi 2.

Referring to he drawings, a furnace, designated. generally as 1 comprises a plurality of walls 2, 3 and 4, a roof 5 and a floor her 7, defined door .8.

Within the furnace chamber and covering the side walls thereof are a plurality of resistance heating units, such as 10, 11, 12, 13, 14 and 15 These units rest, at their bottom edges, upon the floor. of the furnace chamber and lie flat in laterally juxtaposed by these -walls, through a relation along the side walls. The resistance units'are shown disposed along the side walls purely as a matter of convenience, and it is obviously within the scope ofmy invention to dispose them on the top or bottom walls, or both, if desirable.

Each resistance unitcomprises a support or base 20, preferably of nichrome or other heat resistant material, upon which is mounted a plurality of blocks 22, of insulating material, which secure and space a plurality of convolutions of a continuous resistance element 24. One of the longitudinal edges of said base is extended to form a relatively narrow terminal extension 26 for the resistance unit, which extends through aslot 28 in the furnace roof 5. Blocks 23 of insulating material secured to said terminal extensions, support and insulate from each other, the terminals of the resistance heating element 24.

The combined thickness of a block 23 and the base to which it is secured is substantially the same asthe width of'a slot, so that, when in operative position, the terminal extension closes that portion of the slot through which it extends- The terminals are electrically connected to a suitable source of power and, preferably, are so connected as to permit independent electrical energization thereof.

The particular construction of the resistance units constitutes no part of my invention and any desirable means of securing the convolutions of the resistor to the base may be employed.

I provide a slot 28 for each three adjacent units, which slot is considerably less in length than the combined widths of the three units associated therewith, but is greater in length that the width of a single unit. The units are symmetrically disposed with respect to the slot, with the terminal extensions of the first and third units disposed adjacent to the that, upon the removal of the blocks 30, the central units of the groups are fully exposed through the respective slots thereof and may be readily withdrawn therethrough. The other two units in each group, only the terminal extensions of which are disposed in the slots, may then be successively moved laterally into full registration with said slots and removed therethrough.

In the event of a broken or defective heating unit, the block 30 of the respective group is removed, thereby permitting the withdrawal of the central unit of the group through the slot. The next adjacent units may then be successively moved laterally into registration with the slot and removed therethrough. The units are all electrically connected for independent operation so that it is necessary only to disconnect the elements-of a single group to effect the replacement of a defective unit.

It is obvious, therefore, that, by my inven- I tion, an improved structure is provided whereby a defective heating unit may be readily removed without the necessity of completely shutting down the furnace, and the slots through which the units are removable are relativel short, as compared with the total length 0 the units associated therewith. It is possible, therefore, to dispose the heating units to completely cover a furnace wall, floor, or roof, while the effect on the structural strength of the slot-ted wall is reduced to a minimum.

While I have shown and described aparticular embodiment of my invention, changes may be effected therein without departing from the spirit and scope thereof, as set forth in the appended claims.

I claim as my invention:

1. In an electric-resistance furnace, the combination with a plurality of walls defining a furnace chamber, of a plurality of heating units disposed along one of said walls and means permitting the successive removal of said units through a slot in an adjacent wall, the effective length of said slot being less than the combined widths of two of the units disposed thereunder.

2. In an electric-resistance furnace, the combination with a plurality of walls defining a furnace chamber, of a group of three independent resistance units disposed in laterally juxtaposed relation along one of said walls, a slot in an adjacent wall of said chamber disposed in alinement with the intermediate unit of said group, whereby said intermediate unit and a portion of said adjacent units are exposed through said slot, and means permitting the withdrawal of said intermediate unitthrough said slot and the withdrawal of said adjacent units in sequence after the withdrawal of said intermediate unit.

3. In an electric-resistance furnace, in-

eluding a furnace chamber, a plurality of independent resistance units disposed uniformly along a wall thereof, a slot in an adjacent wall of said chamber in alignment with said units, the effective length of which is less than the width of two of the units disposed thereunder, terminal extensions on said units extending into said slot and nonuniformly disposed therein, whereby one of said units may be readily removed through said slot by a longitudinal movement thereof, the other units being removable therethrough in a lateral and then a longitudinal movement.

4. In an electric furnace, the combination with a plurality of resistance units uniformly distributed along a wall thereof, of. a slot in the roof of said furnace disposed. over said units and of substantially less length than the combined widths of said units, terminal means on each unit extending through said slot and non-uniformly disposed therein to partially close said slot, means cooperating with one of said terminal means to completely close said slot, and means permitting the succesive removal of said units through said slot.

5. In an electric furnace, the combination with a plurality of separate heating units disposed in groups along the walls thereof, of means for permitting the removal of the units of said groups from said furnace in a predetermined sequence comprising a slot in the roof of said furnace over each of said groups, said slots being of substantially less length than the combined widths of the elements disposed thereunder, means carried by said elements and projecting into said slots to maintain said elements in operative position and to partially close said slot, removable means cooperating with said projecting means for e ecting complete closure of said slots, whereby, upon the removal of said latter means, one element in the respective group may be withdrawn longitudinally through said slot the remaining elements successively moved laterally into registry with said slot and longitudinally withdrawn therethrough.

6. In an electric-resistor furnace, the combination with a plurality of walls defining a furnace chamber, of a plurality of resistance heating units disposed along certain of said walls, and means in adjacent walls for permitting the removal of said elements from said furnace chamber in a predetermined sequence comprising slots in said adjacent walls the effective lengths of which are considerably less than the combined widths of the units to be removed therethrough.

In testimony whereof, I have hereunto subscribed my name this 9th day of February, 1927.

ROLLO B. LINCOLN. 

